Support is requested to continue a multidisciplinary program of predoctoral training in cellular, biochemical, and molecular sciences under the auspices of the Department of Molecular and Cell Biology (MCB) at the University of California at Berkeley. MCB is a single Department comprised of 109 faculty in five Divisions: Biochemistry and Molecular Biology;Cell and Developmental Biology;Genetics, Genomics and Development;Immunology;and Neurobiology. Based on this organization, MCB has developed a broad, integrated and interdisciplinary approach to training Ph.D. candidates. The 65 participating faculty listed in this application pursue diverse research problems at the molecular and cellular level, providing research opportunities and appropriate instructional environments for the training of graduate students in: (a) Biochemical sciences (metabolic regulation, enzyme purification, enzymatic catalysis, structure and function of biological macromolecules, especially proteins and nucleic acids);(b) Molecular biology (chromosome structure, regulation of gene expression, DNA replication, recombination, repair, transposition);(c) Cell biology (cellular organization and function, cytoskeletal architecture, cell movement, cell surface receptors, ion channels, signal transduction mechanisms, cell growth control);and (d) Molecular and cellular aspects of development (embryogenesis, pattern formation, cell-cell interactions, neuronal differentiation, apoptosis, and development of the immune system). While enrolled in formal coursework to strengthen and broaden their background, entering students conduct ten-week laboratory research projects in three different faculty laboratories. Based on these experiences, the new trainees select doctoral dissertation mentors. In the second year, students concentrate on research, continue to take lecture and/or seminar classes, acquire teaching experience by serving as Teaching Assistants, and undergo an Oral Qualifying Examination administered by a cross-divisional committee. In years three-to-five, students focus almost exclusively on their thesis research;however, enrollment in at least three advanced seminar courses is required. Weekly divisional colloquia, named lectureships and departmental symposia ensure that eminent scientists are brought to the Berkeley campus to expose trainees to the latest breakthroughs in their fields of interest. Applicants typically have outstanding undergraduate records in the biological, chemical or physical sciences.